San Diego, Calif.

Some 32 feet down, in the chilly 52-degree waters of Mission Bay, we're exploring the HMCS Yukon, a six-decked, 366-foot-long Canadian destroyer. And I can't help but feel as if I'm in a supermarket's produce aisle. There's growth everywhere I look on this massive ship--the sides are coated in round-crowned white plumose anemones that look like overgrown cauliflower heads, strawberry anemones are packed on the third deck and thick green kelp sways over open hatches. We swim diagonally, crossing the stern, and see a good deal of marine life along the way--a scattering of ochre sea stars, blacksmiths and blue rockfish.

San Diego dive operators make the run to the Yukon, and also offer trips to the kelp forests off Point Loma and the ritzy enclave of La Jolla, where the main attraction is a deep submarine canyon that runs roughly parallel to the shoreline. The entire canyon complex is part of the San Diego-La Jolla Underwater Park Ecological Reserve, a protected marine reserve that boasts giant kelp forests teeming with black sea bass, sea lions, harbor seals and, of course, California's state fish, the bright orange garibaldi.

But I've come for San Diego's collection of sunken vessels and artificial reefs less than two miles off Mission Beach. The Yukon is the big mama in the 512-acre San Diego Underwater Recreation Area, better known to local divers as Wreck Alley.

The Yukon

A day before her intended intentional sink date in July 2000, rough seas plunged the Yukon 102 feet to the bottom, on her port side. Numerous entry and exit holes were cut into her sides, and penetration is permitted for divers with proper training. The captain of our dive boat Humboldt gives a simple warning in his briefing: Stick with your buddy, and if you can't see through to the other side of an area, do not enter. So we treat the Yukon with the respect she deserves--especially when visibility on this afternoon is, as it is on many days, just 15 feet max.

Even if you're not trained in wreck penetration, there's plenty to see on her exterior, including forward and aft gun turrets. All manner of cold-water marine life thrives on the Yukon, from the aforementioned anemones and sea stars to spider crabs, nudibranchs, kelp bass, surf perch and senoritas.

The Ruby E

This 165-foot U.S. Coast Guard Cutter is half the size of the Yukon, and if you first dive the Yukon, she may seem even smaller--it's possible to swim several laps around the Ruby E and explore her completely on one dive. She's in 80 feet of water, sitting upright and intact on the sand bottom, slightly listing to her port side. Descend to 75 feet to peruse her from bottom to top, where kinetic schools of half-moon and surf perch mass just above her highest point.

She was intentionally sunk 19 years ago after a career that began in the 1930s. The Ruby E was first designed during prohibition and was slated for a job intercepting rum runners. But she wasn't completed until after prohibition--when she bore her original name, _Cyane_--and instead spent the bulk of her career patrolling Alaska's Bering Sea, then processing fish in Latin America and finally salvaging metal in San Diego.

The ship's exterior is coated in strawberry anemones, but the Ruby E's biggest draw is the wheelhouse. It's possible to work your way inside and imagine yourself at her helm. There's also the strange sight of the captain's toilet bolted down.

After a couple of circuits around the ship, the temperature dips slightly from the 55-degree high at the dive's outset and the 10- to 15-foot vis diminishes. I take the hint and slowly ascend.

The Yukon and Ruby E are only two of the fascinating dives in Wreck Alley. The 110-foot kelp cutter El Rey, in 75 feet of water, is nearby. In fact, The Ruby E and El Rey are so close to one another, they can generally be done as part of a two-tank dive trip. Another wreck, the 315-foot destroyer USS Hogan, is done as a one-tank deep dive.

I know I'll return another day to explore all the riches San Diego has to offer, from the beautiful kelp forests of La Jolla to the other wrecks in Wreck Alley.

InDepth

Getting Around: Mission Bay is located north of downtown San Diego and south of La Jolla. The Humboldt and Lois Ann dive boats are located on Quivira Road, in Mission Bay. From downtown San Diego, take Interstate 5 North to Interstate 8 West, then take the West Mission Bay Drive exit toward Sports Arena Boulevard. Make a right turn on West Mission Bay Drive, then make a U-turn at the first traffic light, then go left on Quivira Road.

Dive Conditions: Water temperatures range between 50 and 70 degrees, with thermoclines likely when diving deep wrecks. Visibility averages between 10 and 25 feet. A 7mm wetsuit, with hood, gloves and dive booties (and an optional lycra dive skin inside the wetsuit) or a drysuit is recommended.